Cedrat Technologies, innovation in mechatronicsCedrat Technologies, innovation in mechatronics

Cedrat Technologies, innovation in mechatronics

FSM for large scale free-space optical communication

P-FSM150S AND M-FSM45 fast steering mirrors

New space giant constellations based on Free-Space Optical Communication (FSO) are a new challenge from many perspectives. Considering the mandatory cost efficiency, with repeatability of performances, and reliability with no defect at customer integration, requires an upheaval in space production and acceptance test methods, when the quantities are beyond several thousands of units.

In this publication CEDRAT TECHNOLOGIES (CTEC) presents the design and test results of the P-FSM150S Pointing Ahead Mechanism (PAM) and M-FSM45 Fast Steering Mirror (FSM) Engineering Models, developed under ARTES project TELCO-B for future FSO constellations. The specific cost-efficient hardware design is presented, dedicated to very large quantities to be manufactured, together with the performance test results over a preliminary batch of EM’s production.

Two mirrors have been designed and tested for both the P-FSM150S and M-FSM45. Both mirrors have been designed in silicon carbide (SIC) material, according to CTEC heritage on NASA/PSYCHE PAM30 project  and have been successfully tested before and after integration on each mechanism.

Mirror design

One of the main design constraints of an embedded optics mechanism is to keep the mirror surface deformation to a minimum to limit the induced optical wave front error below the requirements. On this case, a maximum of 40nm rms RWE at 0° mirror surface flatness is the target (corresponding to a 20nm rms optical surface flatness). To ensure that the specification would be reached, CTEC used tools developed for previous space optical mechanisms projects. Specifically including evaluation of induced surface deformation caused by mechanical biases, thermal deformation as well as optimisation of mirror shape and dimensions.

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